Inorganic Acid Doped Polyaniline/Carbon Fiber Composite Electrode as a Marine Electric Field Sensor

Carbon fiber electrode has the advantages of low cost, good chemical stability, and tunable performance, which can be utilized to develop high performance marine electric field sensors. Polyaniline/carbon fiber (PANI/CF) composite electrode doped with hydrochloric acid, sulfuric acid, and phosphoric acid are respectively fabricated by electrochemical in-situ polymerization, and their electrochemical performance and electric field response of the composite electrodes are studied respectively. The results show that conductive polyaniline film is uniformly formed on the surface of carbon fiber, and the characteristic redox peak occurs in the cyclic voltammetry test. Electrochemical impedance analysis shows that the low frequency (0.01 Hz) impedance of PANI/CF composite electrode decreases to at most 1/118 of that of the blank electrode, which is conducive to the quick response to weak underwater electric field signal. In the electric field response performance test, the potential drift of hydrochloric acid doped PANI/CF composite electrode is as low as 1.77 mV/d and it can better respond to 1 mV/10 mHz low-frequency and low-intensity electric field signal. It also has the minimum linearity error (0.111%), indicating the best response sensitivity among these modified electrodes. The preparation method of the composite electrode is simple and low-cost. Therefore, it is expected to be developed into a new generation of marine electric field sensor with low cost and high performance.